Telephone-exchange system



Jan. 13, 1931. Y J. R. GOULD 1,788,517

TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1928 5 Sheets-Sheet 1 Fla. 1

FRP

A T TURNE Y Jan. 13, 1931. J. R. GOULD 1,788,517

TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1928 5 Sheets-Sheet 2 //vvE/v rm? J. R. Goa/.0

A 7' TORNEY TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1928 3 Sheets-Sheet 3 FIGJ //v VEN 7'0? J. E. GOULD reen t in states. 3

TENT IQFFIC' Jonn a. GOULD, or ALIJWY H; Lennon, ENG AND, ASSIGNQB 'io Wns'rnnn nnnc'rnre COMPANY, moonronn'rnn, or new Yomgn. Y, eooiarone rion on NEW Yon-K TELEPHONE-EXCHANGE sYs'rnM Applieationifiled December 5, 1928,'Seria1 no mamas ea -eaten December '13, 1927.

This invention relates to improvements in or relating to automatic and semi-automatic systems and apparatusand consists more particularly inimprovements or modifications in 1 operators key sendingequipments of the kind provided with registering and impulsesending ni'cchanism; i

One of the objects of the invention'is to effect an economy in apparatus and a simpliefiiciency of the facilities afiorded by the equipment. i f 7 One embodiment of the invention specifically setforthcomprisesan operators key sending equipment in which a key set is provided connected in permanent multiple relation with all of the link circuits having access to impulse sendersand to junction lines, each link circuit being provided withswitch ing means for operatively associating the key set therewith. In. addition there is associated with the key set a cancelkey whereby a false registration may be canceled prior to its completion and a start-key whereby number of digits may be employed; The conconductors as thedigit keys. Impulse senders are prov ded having relay reg sters opera registration for controlling the operation of automatic switches and in response to the cancel and start keys to perform other tune tions. The'registration set up by these ad- 5 ditional keys differs from those set up by the diget keys: that of the cancel key maintains the connection between the impulse sender and the link circuit while wiping out all registrations and restoring the digit distribef! uting switch tonormal; that of thestart key advances the digitdistributor to the group of positions in which it: controls-selections and thereafter to the position in which it controls the dismissal of the sender.

The operation ofthis-embodiment of the invention will be more clearly understood from the followingdescription and the accompanying drawings in which:

Fig. 1" shows a junction terminating ina junction relay set J B and having associated fication of the circuits without impairing the I bers containing less than the maximum nume therewith an assignment key ASK and a junction lamp J L. The ope'rators digit keys 1 to 19 and 0, and an outlet relay set comprising a junction finder JF and a sender finder SF are also shown in this figure.

Figs. 2- and 3 show a-registering and 1mrelaygroup, of which there is asmal'l'numbet (3 or 4) per position," a free, one being alreadypres'elected. The two switches hunt, the junction finder JF tojfind the assigned junction andfthe' senderfinder SF to find a free sender Figs. 2 and '3. Senders are available toall of a group of operators, and when onehas been, found, the junction lamp J L associated with the as'signed'junction glows,

giving a signal that the callshould beset V (The junction lamp also flickers if the dis taut operator'takes an unassigned junction,

p "giving asignal to't'he B operator.) ating in response to the digit keys'to take 7 taken the allotted junction, the sender sends out the callas loop impulses to the automatic selectors, via the outlet group and thejunc tionj'group. If the operator has not taken the junction, the'senderwaits for her to do so, andili' this'has-notbeen done after a certain length of time, clears down all circuits by a time pulse. At the endof sending out,-the sender switches the "junction groupifto a throughtalking connection, and clears down" the, outlet group and itself. The junction,

group gives a transmission bridge and sup peIVlSlOIl tomanual exchange and local sub 'scriber, under control of the manual exchange operator.

lVhen a set-up is completed, the outlet group is placed under the control of the send- 1 clears down all circuits immediately if she. has not done so. i

.The operator may, having set up a wrong number, cancel the set-up and set up the call again, provided a complete call was not set up. This is done by a key on the position.

Where all numbers have not the same number'of digits the set-up is completed by depressing a start key on the position afterthe set-up of any number: having less-than the maximum number ofrdigits. For a maximum number of digits the key 1s not used.

This caters for a mixed'digit area and also for short-numberedservicecalls, such as phonograms, etc; sender subsequently sends out the correct number ofdigits and then clears down. j 1

In the present embodiment the key send ing equipment isarranged' for four digit (or mixed 1, 2, 3 and 4 digit) numbers, four out-f let groups per position, and a maximum of unctions per position, but the invention is applicable to any arrangement of'these quantities. The incoming order wire andother operators circuits are notshown since they do not affect the key sending equipment. The operationoit the circuits in greater detail isasfollowsz Circuit Operation relay AS operates fromfthe assignment key ASK viaback contacts B4, and locks to ground at contacts'ASS. Belay AS grounds the common start lead at'contacts AS'Z, re-

moved ground .trom the P contact of the.

junction finderbank and connects the P contact to relay B at contactsAS,disconnects the. outgoing trunk wires at contacts AS1 and AS2, and connects the junction lamp J L tothe outlet groups over a common lead at AS6.' If the distant A. operator has already taken the junction, relay L will beoperated from the distantexchange over the positive line'andthe lamp will be flickering viacontacts B5,,AS6,L1, B1, and the flicker lead ER; on. assignment flickering-ceases. The common start lead is connected to contactsgingchain of all. outlets. VVhen any outlet. is busy, PX relay will be operated (or KK in special circumstances as described latsrlse. hat theground QnAS opera es relay SJ of the first free outlet, via back contacts SJ 5 and KK7 of all outlets, front contacts PY3 of the first busy outlets, back con-' tacts PY3 of first free outlet, and outlet disconnect key ODK. In the present instance it is assumed that the outlet group shown in full is the second outlet, the first outlet group being busy. Relay SJ locks at SJ 5 to the same start lead ground via contacts SJ 5 and KK7 of preceding outlets in chain,-so as to prevent interference to or from other outlets. Relay SJ closes the circuits of junction finder magnet JFDM at contacts SJ 2 and sender finder magnet SFDM at contacts SJ L, and

circuits of relay KS at contacts SJ8 and relay KJ at contacts SJ 1. Both finders hunt, their magnets operating from ground on P bank contacts of busy senders and unassigned junctions respectively. During huntrelay KS is short-circuited by ground on both sides of its winding.

When a free sender is found the magnet SFDM stops, relay KS is no longer shortcircuited and operates via outlet disconnect key ODK and contacts 'SJ 3, in series with sender; finder magnet SFDM. Then the as: signed junction, from whose P bankcontact ground has been removed at cont-acts AS4, is found thema net JFDM stops. Relay KS at contacts K 3. grounds the sender P bank contactfto busy it, lights the outlet lamp OL at contacts KS5 to denote a busy outlet, operates relay KK at contacts KSQ'Via contacts PY2, connects relay PY to wiper ST and disconnectssender chain wire St) at contacts KS4, grounds one side of the winding of rewipers W, X, Y, Z tothe digit keys at contacts I-IK1,KK2,KK3, KKi, lights the junction lamp J L at contactsKKG over the common V j I lead to the assigned junction groupvla con- When the B operator-assignsa junction,

tacts AS6 and B5, holds relay KS at contacts KK5, and closes another point in the circuit of relay PY' at. contacts KK7. 'Thejunction' lamp JL glows as a signal for the operator to setup the call for that junction. When the assigned junction has been toundv relay KJ operates via contacts KS5 and SJl, insedescribed circuits itIwill be seen thatthe call can be set up independently. of the junct on being found.

Relay Bin the junction groupnow oper;

ates from the ground on .Pbank contact via contacts AS4, changes over relay AS at cont tslits astoholcli in,parali i ithm B, keepsthe lam J L glowing at contacts B5 independently of the outlet "group, prepares the output control circuit at contacts B1, and removes ground from the start lead at-coutacts B6. Relay SJ therefore restores, and prepares a circuit to relay PY viacontacts KK7; relays KJ and KS hold.-

Relay BG, Fig. 2, in the sender operates from ground on the P bank contact viacontacts BQ3, connects up relay DS at contacts BG3, disconnects the homing circuit of switch D1) at contacts BGl, provides ground at contacts 3G4 for relayj SS and at contacts BGG for the storage relays, etc., closes atfcontacts BG5 a point in a chain circuit which will be completed over similar. contacts intlie other senders (represented by the dotted connection BE) to transmit earth over lead SC to operate relay PY in the outlet relay group, when all the senders are busy, connects up. time pulse lead TPl at contacts BS7, connects up supervisory lamp SL at contact-s BGZand earths the impulse-motor start wire MSl at contacts BGS. RelaySZ also operates from contacts BGG Via contacts M134 and ST3, and

prevents the operation of relay CC, V

VThere is a group of four storage relays MW, MX, MY, MZ CW, CX, CY, CZ, etc. Fig 3, for every digit of numbers to be setup; the lower operating windings are wired to the banks of switch DD as shown in the diagram and their contacts are wired inmultiple to the banks of switch S. In the drawings, the switch DD is shown'wired fora maxi; mum number of 4 digits, and four. groups of storage relays are shown.- The wiring from- WV, X, Y, Z, first contacts of banks DD6, DDS, DD, DD3 of switch'DD tolower'windings of relays MW, -MX, MY,'MZ' offgroup' M (thousands), thence to battery via the common relay DS. The operated relays lock on the upper windings to ground at'contacts BG6 via contacts M1342 RelayDS- energizes magnet DDM at contacts DSl andrele'ases when the key is restored, so that switch DD is advanced onestep. VVhenthe next key is depressed a similar circuit is made for one, two or three relays of the hundreds group C over 7 the second contacts and wires ()ofswitchDD,

and similarly for other digits.- "Thusa four 7 figure numberis stored bythe sender storage relays. The wiring of the digit keys is arranged so that, withthe same'arrangement of key s rings as is in general use in? key sending circuits, no undue spring load is brought on any storage relayy' whzm the eornplete" samba has'fbeen stoiied,

(ii e k-4 digits) switch DD will have moved to its fifth position and relaySS is then connected over wiperDD2 to the sender finder ST wiper, ;so that relays SS'and PY operate in series via contacts KS4, sender finder ST contacts'SSi RelayPY disconnects at'c0n tacts PY2 and P1 3 relays KK and SJ which release; Relay KKldisconnectsat contacts KK5 relay KS which releases slowly, disconnects the digit-keys from the sender finder wipers and connectsthese wipers to the-iunc tion finder wipers atcontacts KKQ, KK3 and KK L, and disconnects set u'p' signal lamp JL atcontactsKKfi. RelayPYno'wgroundsjunction finderP wiper via contacts PYl, sender finder W wiper,wiper and-bankDDG andflcontactsBQl ;inplace ofcontacts KS1; Contacts P1 4 hold relay'KJ and light outlet lamp OL in place of contacts KS5. Relay KS, removes ground 'from'the sender release trunk, which is now grounded by relay SS in the sender,

so that the outlet is held by the sender. The

operators peg count meter is operated over lead 'PMduringthe' release of relay KS via contacts KSQ and .PYQ. Contacts PYi-l and KK7 together remove the start lead from this outlet and {switch it'to the next free outlet, so that a new assignment can be made.

[The call now proceeds independently of the B operator. and waits for the A operator to take the junction, if sh has not already done sol When the'junctionis taken,

relayST'in the sender operates viacontacts SS2, send-er finder Z wiper. contacts KK KJS, springs of outlet disconnect key ODK, junction finder QC wiper, contactsg-LLBl and ASL, (relayL being energized :fromthe "distant exchange). 1 Relay ST locks via "0011} tacts ST2 to BGG,disconnects-relay SZ at 'contafcts S T3, andrelay Tl? (if-operated) at contacts ST2; (the opening ofcontacts ST}. is ineffective at this time).- The line'relay of the automatic first selector has been operated by-t'he operationot contacts SS3, via contacts'SAQ, and the loop springs LS in parallel, sender finder'wipers'X'and Y, contacts KK2 and KK3, Kill and KJ2, junction finder and +flw'ipers; This selector returns ground on the first selected release trunk to the junction group to hold relay B-j-of the latter and energi'ze the right hand winding ofshuntfieldrelay D; The sender analysis meter is operatedover wiregAM an'drcontacts ST4 to'register an efiective call.

)Vhen relay 'ISZ. has released, circuit is a made for relay rviarthefmagnet impulsesprings MGSQQThemagIIet and loopsprings MGS and LS are opened and closediat interruptions per second each, by'the motor. controlled over contacts RG8. The open period of the loop springs is twice the closedperiod,

similarlyto the subscribers dial, andthej magnet springs are closed and open while loop sprlngsare open and closed respectively.

When the first closure of magnet springs o'c- W hen the magnet-springs closeagain, magnet SDM is again energized, while at the same time the loop springs open and give one pulse to the first selector A relay. .When. the magnet springs'open again the loop springs close,

sothat the switch S makes one stepandthe first'selector A relay reoperates. Thus a series of'impulses is sent out,.rela-y CC and SA remaining operated. The double operation of relay CC ensures thata clipped impulse cannot be applied. tothe magnet SDM, to save undue wear on its mechanism. m

When the correct number of impulses 'corresponding to thefirst digit stored has been sent out, wiper 2 of switch S will have arrived at the corresponding contact (counting from the firstbank connection), which will be grounded via the-operated contacts of the first group M, of storage relays, 5th contact and wiper of'bank D133 and contacts SS1. Relay SZ therefore operates -to this ground via wiper S2, locks viaicontacts .SZ3 and SA3, short circuits the sending loop at contacts SZ2 to prevent turther impulsing, andreleases relay CC at conta'ctsSZfl (contacts SZl are ineffective at this time) When relay CC has'restored, switch S returns home under self-interruption via contactsCC3 to ground via bank S1 and relayTRAj-which' relay operates inseries. Relay-RA gives a slow-operating alarm: over lead RA it the switch fails'toreturn' home. Relay SA- holds in parallel but restores slowly when switch S has returned home. When relay SA, has restored, the sending loop is re-sho'rt circuited by SAQ, relay SZ is restored slowly at contacts SA3, and magnet DDDM'is released so that switchDD'stepsone; /Vhen relay-SZ .has released, the circuit is again made for relay CO at contacts-SZ', the short-circuit on theisending loop'at contacts-SZQ is re moved butremains at contactsSAQ, and the locking contacts'SZiiare openedif a The same series of operations-then proceeds' as after the previous releaseotrielay S,Z, except that switch I DD has moved, one

step meanwhile Relay SZ therefore operates when the switch S has stepped to the contact corresponding to the second digit, since its operating ground will be obtained via the contacts of the secondhundreds group, C, of storagerelays, lead C,6th contact and wiper-0t bank DDB and contacts SS1. The correct number of impulses for the second digit stored is thus sent out, and so on for the remaining digits. The slow-release times of relays SA and SZ between digits, together with the operating'time of relay CC enable the group selectorstohunt for thenext switch before the neXt digit is sent out.. 7 TW-hen relaySZ has released after operating for the end of the last digit of the numher, a circuit is made for. relay BQ, which operates on the upper winding Via contacts SZl, 9th contact and Wiper of bank DB3, and contacts SS1; Relay BQ locks at BQl, grounds the releasetrunkand disconnects relay BG at contacts BQ3, keeps the chain circuit closedat contacts BQ L, flashes the sender lamp 'SL-at contacts BQQ over'interrupted ground on lead 1G to denote clear-down, and removes ground from banlrDDtS at contacts BQI. This .lastreleases relay AS in the junction group, which has been holding. via

junction finder P- wiper, contacts KJ 5, PYl,

sender finder W wiper, wiper and bank DB6 commoning contacts BQl. Relay AS on release places thejunction group transmission bridge across the group selector to hold it, under control ot-the A operatoryia contacts L1. Relay B is now held by the group selector release trunk, keeps the junction lamp JL alight at contacts B5, maintains the assignment lead disconnected at contacts B4, and maintains the selector loop through at. contactsBl and B2; 7 I At the same time relay 13G; releases in the sender, closes the homing circuit for magnet DDDM at contactsBGl, opens the time pulsecircuitat-contacts'BG'Z, releases relay TP, ST andstora e relays andprevents oper-. at contacts RG6, andgrea leases relayP Y inthe outlet group and re ation of relay lay SS at contacts BGl. Relay BY. restores and releases relay KJ and vezittinguishes the outlet lamp OL at PYt. Relay KJ restores and disconnects the. sender from both junction group and outlet group. Relay PY at contacts PYEB reconnect-s the start lead to relay SJfor anewset-up. Magnet DDDM homes its switch via bank DDI inseries with relay RA, whichoperates; RelayRA gives the alarm at, contacts RA2 if the switch fails to return, and holds relay BQ, overitslower winding at contacts'RAl. Relay BQ keeps the sender busy at contacts. BQig, the chain circuit-closedat contacts BQsand the lamp SL flashing at contactsBQQ, until the sender hascompletely restored tonormal, when relays. RA and BQ, release,

- When; the. ca led subscriber answ rs; 9

rent is reversed back to the junction group so that "shunt field relay D operates and at to the distant operator. If, however, a busy:

selector has been found, relay I flashes, due to the periodic short-circuiting of the selector loop by busy flash from the busy selector. Relay 1 then connects relay L periodically to the ve line to flash theldistant supervisory lamp, for a busy signal.

The circuits also provide other features as follows: p r

(a) II the operator, having made a wrong set-up, desires to cancel the setup and start again, she depresses the cancel key C, which is wired in common with the digit keys. The depression of this key energizes the X and Z relays of the particular storage group on which switchDD in the send-er is resting, in the same way as for, a digit key. The X and Z combination is not used for a digit, so that it is never made by a digit key. This combination however provides a circuit for relay BQ, which operateson the upper winding via contacts CW3 (back) assuming that the X and Z combination of the 100s group is energized) CZ6 and CXel (front) DX l and UXd (back) wiper and bank DDl (any con-' tact 2l) and relay RAt-o ground,

Relay BQ releases relay BGatfcontacts BQ3, and keeps sender chainpclosed at contacts BQet. Relay. BG on release releases the storage relays at contacts BGGand disconnects the timepulse at contacts B'G'Y, and

completes the homing circuit of magnet DDDM at contacts-BGL The" circuit for driving the switch DD to its fifth position extends via magnet DDDM, its interruption contacts, contacts BG-l, a chain circuit including back ,contacts MXe, DXt,

UXa of allthestoragegroups,commonedcontacts and wiper of bank DDl, and relay RA; in position 5 the magnet DDDM operates via contacts BGl, commoned contacts 5to12, and relay BA. f RelayR-A operatesand holds relay BQ via contacts RAJ. until the switch is home; Relays RA and BQ then release and relay BG reoperates, in readiness for a new set-up. The time pulse has now been reset, so as to give the operator "full time for a new set-up. 7

(b) If in any area it is desirable to send numbers having a fewer digits than the full number, (suchas calls toiservices or in mixed digit areas) a start key Sis fitted on the position. The operator depresses this key after setting up the short number. and the 't', X and Z combination in the particular storagegroup on which the switch stands are operated in the sender in the same way as for a digit key, this combination being also not used for a digit. Assuming the operator has set a numb'er comprising one digit thisoperation causes the magnet to be energized via its interruption springs,

contacts CWVB,CZ6 and OX4 (front) DX land UK; (back) bankDDl and relay BA toground. I Since the storage relays remain locked us asiusual" the switchmoves onl to the position of complete set-up (5th -posi-. ,7

tion on the'draii ing so-th'a't the, sender then prepares to send in thefus'ual way. .i (If a two, digit number had been sent this circuit would-have extended over contacts DNSS, D36, and DX l, i hen sending com mences, thestored' digits are sent out, but when wiper DD3 of control switch DD arrives atflthe contact corresponding to the storage group operated by the start key, it willf'not mark any point on the bank S2 of switch S,but instead prepares a circuit for relay BQ. Thus, when relay SZ has released after its operation for the previous digit, relay'BQ operates on itsfupper winding via contacts SZ'LGZQ oi the particular storage group concerned, 0Y2 (back), OX2, Cl' A, bank and Wiper of bank DB3 and contacts SS1 to ground. This causes the sender to clear-dowh in the regular manner, having sent only the correct numberof digits. The junction group then switches through and the outlet group clears down in the usual way.

I \V hen all the numbers have the same full number of digits contacts 'CZQ', DZQ, U22, ClVS, DlV3 and UVV3 will not be required the back contacts lVlXt, (3X4, DX l, UX t will be omitted, the armatures operatingcontacts MX l, CXtfDX h UXe will be con:

nected in parallel and the whole of blank DDl commoned. p

(c) If the operator has made an incomlete set-u the sender cannot )IQ are to send and the call therefore has to be cleared Out-eitherby-e 1 (1) Assignmentpoi' a fresh call or (2) Timepulse. I (1) If the sender has not prepared to send, relay PY has not been operated, relay KK is still operated, and wiper of bank DDQ of switch DD is on acontact before the posi tron of complete set-up (1. e; conta'ctslf1-) It now the operator assigns fresh junc tiongroup, ground from AS? energizes reagerela'ys'and relay SZ whichrelease, and connects bank DD2 to its magnet DDDM at contacts MBl. RelaySS prepares the sender for sending in the usual way, and the" ground via contacts SS6 operates relay PY and also 7 net isthen disconnected by the bank commoning, so that the sender is now in the usual start-send position except that relay MB is also operated.

lVhen relay PY has operated and .KK released, the ground on the commonstart lead is switched to the next outlet, which therefore proceeds to function for the new call. A special call is now sent out, depending on the cross-connection on terminal strip MS, and providing that the distant operator has taken the junction. On the operation of relay MB relay SZ releases, and if the operator has not taken the junction whenrelay SZ has released, relay BQ, operates via contacts SZl, STl, back contacts MZ5, MY5, MX3, MWQ of first storage group, bank and wiper DB3, contacts SS1 to ground. Belay BQ causes the sender to clear-down in the normal manner, followed by the outlet and junction res lay groups. If, however, the distant operator has taken the junction, relay ST operates and locks over the output control circuit, as described for the regular call, so" that on release of relay SZ the above circuit for relay BQ, is disconnected by contacts STl. The sender therefore proceeds to send out in the usual way, but the storage groups, being released, provide no marking ground on bank S2 of switch S via their front contacts but ground the terminals 1114 of terminal strip MS, via all their back contacts MZ5,.

MY5, MX3, MVV2,-etc. The MS terminals are cross connected to terminals I10, which are commoned to bank S2 of switch S, or to terminal 15. Thus if terminal 11 is connected to terminal 5 the sender will send out a first digit of 5, and so on for other digits. If any terminal 1114c is jumpered toterminal 15, the relay B'Qfiwfillbe operatedvia contacts SZl, MS15, MSll, 12, 13 or 1%, back contacts of corresponding storage relays, bank and wiper DDS, contacts SS1 to ground. By this means the sender can be made to cleardown immediately (using connection MS11 to MS15) or after any number of digits, thus leaving the junction g'roup'on the first group selector orswitching the call to any desired manual operator.

(2) If the operator'has made an incom I plete set-up but has notreassigned within a sender by contactsBGT' as soon as the sender has been found. At the first impulse :rela'y TP operates over itsupper winding via contacts TF2 and BG? and closes contacts TPl only, and when the" pulse, goes," relay TB operates fully on both windings to ground at contacts BGG via contacts ST2 andlTPhand changes over the time pulse lead to relay MB at contacts TF2; If the operator sets upcthe call and the distant o erator by taking the junction causes relay T to energize before the time pulse interval has elapsed, relay TP is disconnected by contacts ST2. the second time pulse operates, via contacts TP2, relay MB, which looks on its upper winding. Relay MB then causes the special call to be sent out or the sender to clear-down in the same 'manner as in (c) The double operation of relay TP gives the B operator at least the timepulse interval in which to set up the call. 7

(cl). If the operator makes a complete setup, but the distant operator fails'to take the junction before the advent of the second time pulse, relay MB operates as'before. The special call is then sent out if the distant op'-' erator then takes the junction before the release of relay"SZ, (which is an unlikely event) or thesender clears down immediate ly as described before.

(e) A key is associated with each sender and each outlet group'to facilitate testing of the circuits and cutting out of faulty Cir cuits. The outlet 'dis'connectike'y ODK, when thrown, lights the associated outlet lamp OL, disconnects relay SJ and switches the common start lead to another outlet, and disconnects relay KS. The sender busy key BK connects its lamp SL over the supervisory key SK ground, grounds the sender release trunk and closes the chain circuit in order to keep the sender busied, and disconnects the release alarm and meter leads. The supervisory key SK is commonjto a group of senders, and when throwncauses the lamp SL of all busy senders to light over contacts BS2.

(f) In order to prevent unnecessary running of sender finders when all senders in the group are busy, a chain circuit is used, connecting all senders of the group by means of contacts BG5, BQ4 and busy key springs in parallel. This chain completed whenever all senders in a group are busy or out of service, and immediatelyoperates relays PY in'parallel of all outlets whose sender finders have access to this group of senders, except those outlets which have found a sender before the chain circuit was completed. Relay PY operates via back of contacts KS4. and, 7

KJ 6 if a sender has not been found, lights the outlet lamp OL at contacts PY4:, and dis connects relay SJ and switches the common start lead to the next outlet, at contacts FY23.- If relay SJ was operated by an assignment, it new releases and stops the finders hunt-l ing, and the assignment passes to another outlet associated with another (free) group of senders.

If not, i

What is claimed is:

1. In a telephone'system, ,a key set comprising a single row of digit keys, an impulse sender comprising a plurality of registers, means to set said registers in response to the repeated operation of said key'set, means responsive to the setting of all of said registers to initiate a selective operation, an additional key efiective to establish a registration upon any one of said registers difi'erent from the digit registrations, and means responsive to the establishment of said dif-' ferent registration to initiate said selective operation.

2. In a telephone system, a key set comprising a single row of digit keys, an impulse sender comprising a plurality of registers, a digit distributing switch for successively connecting said key set to said registers whereby said registers may be set in response to the repeated operation oif said key set, means responsive to the setting of each of said registers to advance said digit distributing switch, means controlled by said switch in the position taken following the setting of the last register to control a first selective operation, an additional key efl'ective toestablisli a registration different from the digit registrations, and means responsive to the establishment of said difierent registration on any one of said registers to advance said digit distributing switch directly to said selection controlling position. I

8. In a telephone system, a key set comirising a single row of digit keys, an immlse sender comprising a plurality'of regis- "ers, means to successively connect said key set with said registers whereby said registers may be set in response to the repeated operation of said key set, means responsive to the setting of all of said registers to initiate a selective operation, additional keys effective to establish registrations different from the digit registrations, and means responsive to the establishment of said difierent registra' tions to cause said sender to function in a manner different from a normal registration.

i. In a telephone system, a keyset comprising a single row of digit keys, an'impulse sender comprising a plurality of relay registers, a plurality of conductors connecting said key set and said impulse sender, means to successively connect said conductors with sender. I

.my name this ltlth day of November, 1928.

prising a single row of digit keys, an impulse sender comprising a plurality of relay registers, a plurality ofconductors connected with said keyse't, a digit distributing switch for successively extending said conductors to said registers whereby said registers may be set in response to the repeated operation of said key set, means responsive to the set.- ting er cachet said registers to advance said digit distributing switch, means controlled by said switchin the position taken following the setting of the last register to control a first selective operation, an additional key connected with said conductors and efi'ective to establish a registration diiierent fromthe digit registrationmand means responsive to the establishment of said dil'lerent'registra tion on any one of said registers to advance said digit distributing switch directly. to said selection controlling position.

tions, and means responsive to the establishment of said different registrations to cause said senderto functionin a manner different from a normal registration.

7. In a telephone system, a plurality of digit keys, an impulse sender comprising a plurality of relay registers, means to associate said keys and said registers, means to position said registers under the control of said digit keys, an additional key effectlve to establish a registration different from digit registrations, and means responsive to said different registration to wipe out said registration without releasing said keys from said In witness whereof, I hereunto subscribe JOHN R. GOULD.

said registers whereby said registers may be set in response to the repeated operation of said key set, means responsive tothe settlng of all of said re isters to initiate a selective operation, an additional key. connected with said conductors and eflective to establish a registration upon any one of said registers diiferent from the digit registrations, and means responsive to the establishment of said diii erent registration to initiate said selective operation.

5. In a telephone system, a key set com- 

